The submarines of the Kaichu V sub-class were designed for anti-shipping operations and carried more fuel and had greater range and a heavier gun armament than preceding Kaichu-type submarines. They displaced 866 tonnes (852 long tons) surfaced and 1,036 tonnes (1,020 long tons) submerged. The submarines were 74.22 meters (243 ft 6 in) long and had a beam of 6.12 meters (20 ft 1 in) and a draft of 3.73 meters (12 ft 3 in). They had a diving depth of 45.7 meters (150 ft).

For surface running, the submarines were powered by two 600-brake-horsepower (447 kW) Sulzer diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 600-horsepower (447 kW) electric motor. They could reach 13 knots (24 km/h; 15 mph) on the surface and 8.5 knots (15.7 km/h; 9.8 mph) underwater. On the surface, they had a range of 9,000 nautical miles (17,000 km; 10,000 mi) — although the Imperial Japanese Navy officially announced it as 6,000 nautical miles (11,000 km; 6,900 mi) — at 10 knots (19 km/h; 12 mph); submerged, they had a range of 85 nmi (157 km; 98 mi) at 4 knots (7.4 km/h; 4.6 mph).

The submarines were armed with four internal bow 533 mm (21.0 in) torpedo tubes and carried a total of eight torpedoes. They were also armed with a single 120 mm (4.7 in) deck gun and one 6.5 mm machine gun.

Ro-29 was laid down as Submarine No. 68 on 2 June 1921 by Kawasaki at Kobe, Japan.^[1] Launched on 5 December 1922,^[1] she was completed and commissioned on 15 September 1923.^[1]

Upon commissioning, Submarine No. 68 was attached to the Sasebo Naval District, to which she remained attached throughout her active career.^[1] On 1 June 1924, she was assigned to both Submarine Division 25 — in which she spent her active career — and the Mako Defense Division headquartered at Mako in the Pescadores Islands.^[1] She was renamed Ro-29 on 1 November 1924.^[1] On 1 December 1926, she was reassigned to the Sasebo Defense Division, headquartered at Sasebo, Japan.^[1] Her service in the Sasebo Defense Division ended on 15 November 1934, after which she served as a unit of Submarine Division 25 in the Sasebo Naval District.^[1]

Ro-29 was decommissioned and stricken from the Navy list on 1 April 1936.^[1] As a hulk, she was renamed Heisan No. 9 on 1 April 1940.^[1]

• "Rekishi Gunzō"., History of Pacific War Vol.17 I-Gō Submarines, Gakken (Japan), January 1998, ISBN 4-05-601767-0
• Rekishi Gunzō, History of Pacific War Extra, "Perfect guide, The submarines of the Imperial Japanese Forces", Gakken (Japan), March 2005, ISBN 4-05-603890-2
• The Maru Special, Japanese Naval Vessels No.43 Japanese Submarines III, Ushio Shobō (Japan), September 1980, Book code 68343-44
• The Maru Special, Japanese Naval Vessels No.132 Japanese Submarines I "Revised edition", Ushio Shobō (Japan), February 1988, Book code 68344-36
• The Maru Special, Japanese Naval Vessels No.133 Japanese Submarines II "Revised edition", Ushio Shobō (Japan), March 1988, Book code 68344-37
• The Maru Special, Japanese Naval Vessels No.135 Japanese Submarines IV, Ushio Shobō (Japan), May 1988, Book code 68344-39